It's important to freeze out cryotherapy misinformation

By Susan Kwiecien, PhD

Misinformation is rampant in the modern age, amplified by the ease of access to information and social media. The COVID-19 pandemic has shown how false information can have serious implications for public health. Healthcare workers have a duty to combat misinformation by promoting evidence-based practices. One topic that has been recently misrepresented is cryotherapy.

Cryotherapy, which involves reducing tissue temperature by withdrawing heat from the body, comes in different forms and can be manipulated to achieve specific health goals. Ice baths, a form of cryotherapy, have been used for rehabilitation for decades, but they have recently become trendy in influencer circles. While some tout its benefits as a holistic approach to improving health, others claim that it does more harm than good. However, neither of those perspectives is entirely accurate. The benefits, or lack thereof, of cryotherapy are nuanced and come with a lot of caveats.

I have a PhD in exercise physiology and wrote my dissertation on the effects of prolonged cooling to accelerate recovery following exercise. As a Clinical Research Manager at Northwell Health’s Nicholas Institute of Sports Medicine and Athletic Trauma (NISMAT) located at the Manhattan Eye, Ear and Throat Hospital (MEETH) I continue to investigate the role cryotherapy has for recovery following not only exercise, but also for recovery following injury and surgery. I have spent a large portion of my academic and professional career as a clinical researcher studying cryotherapy. So, it’s safe to say that I have strong – and well-researched – opinions on the topic!

It is important to understand the physiological response in the body to injury or exercise before we can dive in to understanding the effects of cryotherapy for recovery. Injuries and exercise prompt similar physiological responses from the body, including initial structural changes to the tissue which occur at the time of the injury or during exercise followed by a secondary damage response which occurs in the hours that follow.

During this second phase there is a proliferation and exacerbation of the initial structural damage. The subsequent inflammatory response, which includes macrophage and neutrophil infiltration and further cell death, culminates in a regenerative/repair phase. Essentially, the body undergoes a natural process to recover from the trauma.

Unfortunately, side effects of the healing process include swelling, pain, or that all-too-familiar stiffness and soreness that we associate with a hard work out. We can implement cryotherapy as a recovery modality in an attempt to hack the healing process and accelerate it.

We know from evidence in animal models that reducing tissue temperatures can lower the metabolic rate of the injured area at the cellular level. Albeit seemingly counterintuitive, a local reduction of metabolic rate might attenuate the initial pro-inflammatory steps and ultimately accelerate the anti-inflammatory phase of the healing response. It is in this way that cryotherapy can speed up the overall recovery process.

With this in mind, we have been able to infer that cryotherapy could be advantageous for those interested in accelerating their recovery following injury (or surgery), or for those interested in maximizing their exercise regimen. Nevertheless, cryotherapy can be beneficial for some individuals, but it is not a universal cure and may not be suitable for everyone. Cryotherapy is a great tool for those who must be constantly active like professional athletes, those on strict training schedules, for multi-sport youth athletes, or for individuals wanting to enjoy recreational activities over a few days’ time (e.g. multi-day hike, or ski trips). To optimize the benefits of cryotherapy, our research, as well as others, have recently found that colder isn’t necessarily better, but longer is. A 32°F ice bath not only prevents you from experiencing the therapeutic effects of cryotherapy for a duration long enough to elicit a clinically relevant result, but it also causes deep tissue shivering (which we want to avoid!).

Instead, athletes should opt for milder temperatures. Our research has shown that if you apply cooling packs which maintain a constant temperature a 59°F for three hours immediately after a strenuous activity, your soreness and strength loss recover faster. Keeping the muscles cool – not cold – for as long as possible helps the body recuperate quicker. What’s important here also is to not wait. You want to use cryotherapy as soon as possible after completing your exercise and remember that pain isn’t always gain with cryotherapy!

Cryotherapy can also be a great tool for those undergoing orthopedic surgeries like knee or hip replacements. Many surgeons prescribe cryotherapy machines as a post-operative recovery tool, but it’s often overlooked or ignored by patients. Don’t do that! If used consistently within the first 24 hours of surgery, they have great potential to hasten healing. Their analgesic effect can also help patients looking to avoid taking too much pain medication.

Speaking of avoiding things… those who should avoid cryotherapy are individuals who are looking to build muscle mass (scientifically this is called muscle hypertrophy). Research suggests that chronically lowering muscle temperature can suppress the mechanisms that regulate muscle hypertrophy. Cooling temperatures also trigger the cardiac parasympathetic nervous system which can cause irregular heartbeats. Because of this, cryotherapy is not recommended for those with cardiac conditions, unless cleared by their doctor.

NISMAT, which is celebrating its 50th anniversary this year, is committed to the study of sports medicine and advancing research to not only keep athletes healthy but also ensuring they perform at optimal levels. Through our research into topics like cryotherapy we hope to continue to advance the field and redefine the focus of sports medicine for many decades to come.

Susan Kwiecien, PhD is the Manager of Clinical Research at Manhattan Eye, Ear and Throat Hospital’s Nicholas Institute of Sports Medicine and Athletic Trauma